Process for improving the antistatic properties of synthetic articles



United States Patent 3,313,796 PROCESS FOR IMPROVING THE ANTISTATIC PROPERTIES OF SYNTHETIC ARTICLES Bertie Joseph Reuben, Julian J. Hirshfeld, Byron A. Sample, Jr., and David C. T. Yao, Decatur, Ala., as signors to Monsanto Company, a corporation of Delaware No Drawing. Filed Feb. 24, 1964, Ser. No. 347,050 8 Claims. (Cl. 117-1388) This invention relates to a composition of matter and a method of making the same, and more particularly, to an improved process for imparting antistatic, wrinkle resistance and other desirable properties to synthetic substrates and to the compositions of matter resulting therefrom.

One common disadvantage in using synthetic fibers to comprise fabrics as compared with natural fibers is that they tend to collect static electrical charges, this being objectionable during the wearing thereof. Also, many synthetic fabrics do not have the wrinkle resistant characteristics which some natural fibers possess, such as, wool; therefore, these fabrics must be treated in order to compete therewith. It is desirable on occasion to combine synthetic filaments with cotton, a natural fiber having a low wrinkle recovery but, unless the synthetic fibers have a high resilience or unless wrinkle resistance is not a requirement, the combination would not be feasible for the fabric produced therefrom would not appeal to a purchaser. Synthetic fabrics do not dissipate the electrical charges which have accumulated thereon as readily as fabrics being composed of natural fibers for synthetic fabrics are known non-conductants of electricity whereas natural fabrics distribute their charges over the surfaces thereof. Finished synthetic textile fabrics fail to drape like cotton or wool due to the accumulation of static charges thereon, have a tendency to cling uncomfortably to the wearer, and attract dust and lint thereto. In addition, the electrical discharge itself is bothersome. With the exception of one or two antistatic agents, fabrics having been treated therewith lose the antistatic protection after one washing. Most known antistatic agents useful in the textile arts impart to textile fabrics some undesirable properties, such as, unpleasant hand and discoloration upon application or with continued fabric use. Furthermore, some known antistatic agents are operable only with a narrow pH range and thus lack compatibility with many other common yarn-treating agents which are not stable in that pH range thereby making it necessary to apply the agent in a treatment step distinct from that employed for other purposes. Most of the available antistatic agents are of cationic or nonionic nature, very few are anionics. Although the cationic compounds have a certain affinity to acrylic fiber, there is no known way of permanently uniting them to the fiber. Nonionics have no affinity whatsover to any fiber. A practical approach to the problem of making a lasting antistatic agent may be to cross-link the molecules on the surface of the fiber but to date, this has not been successfully done. Another approach may be to bind these molecules on the surface of the fiber by some adhesive means.

Therefore, a primary object of this invention is to provide a process which will cement nondurable type antistatics to the surface of synthetic fibers, the synthetic fibers being in fabric form, in order to make them resistant to many launderings.

A further object of this invention is to provide a process for imparting durable antistatic properties and Wrinkle resistant characteristics to a fabric which is comprised of synthetic fibers.

Another object of this invention is to provide a process ice which simultaneously imparts durable antistatic protection and wrinkle resistant characteristics to a fabric.

Yet another object of this invention is to provide a novel composition of matter having durable antistatic and wrinkle resistant characteristics.

A still further object of this invention is to provide a product, such as a fabric being comprised of acrylic fibers, with a durable antistatic finish by polymerizing resin on the surface of the fibers by means of a catalyst, the resin during the polymerization thereof bonding nonionic antistats to the surface thereof.

These and other objects and advantages will become apparent in the course of the following specifications, examples, and appended claims.

The invention consists of the finding that certain polymerizable resins enter into reaction with adhesive agents and form a complex molecule. Although some antistats do not exhibit an affinity for synthetic fibers and are easily removable even by rinsing in water, they stick tenaciously to the fiber, after the described reaction with the resins has been performed, the resins serving as a link between the fiber and the antistat.

In accordance with the present invention, a synthetic fabric, such as one being comprised of acrylonitrile-based fibers, is provided with durable antistatic properties by continuously associating the fabric with an aqueous antistat-resin composition which also contains a dispersing agent and a catalyst. This composition also increases the wrinkle resistance of a fabric to which it has been applied.

The use of these antistatic agents, in accordance with the present invention, effects improvement in the charge dispersing characteristics of acrylonitrile polymers and articles produced therefrom. The invention is applicable not only to polyacrylonitrile, but also to copolymers, interpolymers, and blends thereof, particularly those containing at least percent by weight of polymerized or copolymerized acrylonitrile. Such polymeric materials include acrylonitrile fiber-forming polymers with readily dyeable basic copolymers, the blend having an overall polymerized acrylonitrile content of at least 80 percent by weight.

For example the polymer may be a copolymer of from 80 to 98 percent of acrylonitrile and from 2 to 20 percent of another copolymerizable mono-olefinic monomer. Suitable copolymerizable mono-olefinic monomers include acrylicalpha-chloroacrylic and methacrylic acids, the acrylates, such as methylmethacrylate, ethylmethacrylate, butylmethacrylate, methoxymethyl methacrylate, beta-chloroethyl methacrylate, and the corresponding esters of acrylic and alpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinyl bromide, vinylidene chloride, l-chloro-1-bromoethylene; methacrylonitrile; acrylamide and methacrylamide; alpha-chloroacrylamide, or mono-alkyl substitution products thereof; methyl vinyl ketone; vinyl propionate, and vinyl stearate; N-vinylimides, such as N-vinylphthalimide and N-vinylsuccinimide; methylene malonic esters; itaconic acid and itaconic ester; N-vinyl carbazole; vinyl furan; alkyl vinyl esters; vinyl sulfonic acid; ethylene alpha, beta-dicarboxylic acids or their anhydrides or derivatives, such as diethylcitraconate, diethylmesaconate; styrene; vinyl naphthalene; vinyl-substituted tertiary heterocyclic amines such as the vinylpyridines and alkyl-substituted vinylpyridines; for example, 2-vinylpyridine, 4-vinylpyridine, '2-methyl-5- vinyl-pyridine, and the like; l-vinylimidazole and alkylsubstituted l-vinylimidazoles, such as 2-, 4-, or S-methyll-vinylimidazole, vinylpyrrolidone, vinylpiperidone, and other mono-olefinic copolymerizable monomeric materials.

The polymer can be a ternary interpolymer, for example, products obtained by the interpolymerization of acrylonitrile and two or more of any of the monomers, other than acrylonitrile, enumerated above. More specifically, and preferably, the ternary polymers contain from 80 to 98 percent of acrylonitrile, from 1 to 10 percent of a vinylpyridine or a l-vinylimidazole, and from 1 to 18 percent of another copolymerizable monoolefinic substance, such as methacrylonitrile, vinyl acetate, methylmethacrylate, vinyl chloride, vinylidene chloride, and the like.

The polymer can also be a blend of polyacrylonitrile or a copolymer of from 80 to 99 percent of acrylonitrile and from 1 to 20 percent of at least one other mono-olefinic copolymerizable monomeric substance with from two to fifty percent of the weight of the blend of a copolymer of from 30 to 90 percent of a vinyl substituted tertiary heterocyclic amine and from 10 to 70 percent of at least one other mono-olefinic copolymerizale monomer. Preferably, when the polymeric material comprises a blend, it will be a blend of from 80 to 99 percent of a copolymer of 80 to 98 percent acrylonitrile and from 2 to 20 percent of another mono-olefinic monomer, such as vinyl acetate, which is not receptive to dyestuff, with from 1 to 20 percent of a copolymer of from 30 to 90 percent of a vinyl-substituted tertiary heterocyclic amine, such as a vinylpyridine, a l-vinylimidazole, or a vinyl lactam, and from 10 to 7 percent of acrylonitrile to give a dyeable blend having an overall vinyl-substituted tertiary heterocyclic amine content of from 2 to 10 percent based on the weight of the blend.

While the preferred polymers employed in the instant invention are those containing at least 80 percent acrylonitrile, generally recognized as the fiber-forming acrylonitrile polymers, it will be understood that the invention is likewise applicable to polymers containing less than 80 percent of acrylonitrile. Polymers containing less than 80 percent acrylonitrile are useful in forming fibers, lacquers, coating compositions and molded articles.

In accordance with the present invention, these antistatic agents may also be used in combination with other textile filaments, such as polyester fibers and articles produced therefrom. A fiber was formed by extruding a typical polyester melt, such as polyethylene terephthalate, through a conventional spinnerette downwardly through a chimney where the melt was air quenched and was hardened into filaments. The fibers were converged and collected on a bobbin as undrawn yarn. A number of bobbins were then combined and a tow was formed by continuously pulling the yarn therefrom. The tow was heated to at least 40 C. by being passed under a hot water spray. The fibrous tow then passed into a drawn zone where the temperature thereof was increased to 80 C.90 C. by another hot water spray or by a finishing solution and was elongated to at least four times its original length. The dried fibrous tow was then cut to staple lengths and processed according to conventional techniques whereupon it was then made into a fabric.

The antistatic finish is provided by mixing an epoxide resin with a nonionic antistat having the formula:

ll H11 wherein n is a small whole integer less than 10 and for this invention, n=4. The chemical term for this formula is nonylphenoxypoly (ethyleneoxy) ethanol. Such a material is available on the open market and can be purchased under the trademark Igepal by Antara Chemical Company, 435 Hudson Street, New York, New York.

This epoxide resin is polymerized on the fiber by a catalyst, such as for example, zinc fiuoroborate. Such a product with a molecular weight of between about 280 and 360 is available on the open market under the trademark Eponite by Shell Chemical Corporation of 500 Fifth Avenue, New York, New York. Other similar commercial products from the same source include the Epon resins which are diepoxide condensation products of epichlorohydrin and dimethyl, di-(para hydroxyphenyl)methane and the poly(allyl glycidyl ethers).

In order to insure a proper suspension of the abovementioned ingredients, a dispersing agent is added to the mixture thereby emulsifying the same. Satisfactory dispersing agents are the aromatic polyglycol ethers, one example of such being the alkylphenol-polyglycol ether containing 9.5 moles of ethylene oxide which can be purchased on the open market under the trademark Neutronyx 600 and which is manufactured by the Onyx Chemical Corporation, 190 Warren Street, Jersey City, New Jersey.

In preparing this aqueous mixture for its application to the fabric, a catalyst is added thereto to polymerize the epoxide resin. As a fiber comes in contact with the polyepoxide, the latter clings thereto and when it is cured, as will be described below, it forms a veneer around the fibers which is almost impervious to or unaffected by water. The nonylphenoxypoly (ethyleneoxy) ethanol either reacts with the polyepoxide or is trapped by it and is held against or bonded to the fiber for when placed in suspension therewith and cured on the fiber, the nonylphenoxypoly (ethyleneoxy) ethanol cannot be easily removed by washing. It is not known which phenomenon attracts this additive to the fiber but it has definitely been proven as the examples will show that nonylphenoxypoly (ethyleneoxy) ethanol when in combination with the other elements has an affinity for the synthetic substrates. It was found previously that epoxide resins, when polymerized according to the instructions, cling relatively well to the fabric and impart a static protection relatively durable to laundering. This can best be explained by calling the result a synergistic action in which two or more compounds having antistatic properties are combined to form a composition having an antistatic activity higher than the total of the individual additives comprising the aggregate. Since this suspension is applied to fabrics only, the problems of excessive card loading, poor processing on the cotton system and extreme buildup of polymerized material on the heating roll surfaces are eliminated.

The fabric, when treated by padding, spraying, or kissrolling with the compounded finish, is dried, cured at temperatures above 260 F. and then subjected to static evaluation on a Hayeck and Chromey apparatus after being conditioned overnight at 72 F. and 33 percent relative humidity. The evaluation is performed according to instructions given in American Dyeing Ref. vol. 40 (1951) p. 164.

The treated fabric is evaluated, as received, after being dyed and after being laundered until the fabric shows a lack of static protection. The fabric was washed in a washing machine for four minutes at 120 F. with 0.5 percent Tide detergent, rinsed, and centrifuged.

This operation was repeated five times after which the fabric was dried, conditioned overnight and evaluated for static as described. The washings were repeated until no more static protection could be detected. The pro: tection is considered excellent if one half of the static electrical charge (this is called half-life) induced thereon is drained off within seconds, good if drained off within 30 seconds, fair if drained off within 60 seconds and not acceptable if the half-life is longer than 60 seconds.

The wrinkle recovery or fiber resilience is measured on a Monsanto Wrinkle Apparatus. Pieces of non-treated and treated clot-h are tested and if the percent differential of return of the treated fabric is 5 percent or greater, the treatment is considered to be successful. A sample of fabric is laid fiat, folded back upon itself through an angle of 180 and released. The angle through which the fabric returns is compared with the original displacement angle of 180 and the percent of return is thereby calculated.

The following examples are cited to illustrate the invention. It is not intended to limit it in any way. Unless otherwise noted, parts as expressed in the examples indicate parts by weight.

EXAMPLE I v An aqueous dispersion was prepared containing 4.91 percent solids, of which one percent by weight was nonylphenoxypoly (ethyleneoxy) ethanol (Igepal C0430), 3 percent polyepoxide resin (Eponite 100), 0.75 percent alkylphenol polyglycol ether (Nentronyx 600) and 0.40 percent zinc fluoroborate 40 percent solution. This composition was applied to a length of fabric, the fabric being made from acrylonitrile-vinyl acetate copolymer fibers via padding, but the composition may be applied by spraying, dipping, brushing, or any other technique. The length of fabric having been padded with the aqueous composition was then dried at 200 F. after which it was cured at 300 F. for six minutes. The resulting fabric was found to readily dissipate a charge of static electricity and was found to have improved wrinkle recovery qualities after five washings and after ten washings as the following table will show.

An aqueous dispersion was prepared containing 5.7 percent solids, of which 0.5 percent by weight was nonylphenoxypoly (ethyleneoxy) ethanol, 4.0 percent polyepoxide resin, 1.0 percent alkylphenol polyglycol ether and 0.50 percent zinc fluoroborate (40 percent solution). This composition was applied in the same manner as described in Example I to a length of fabric of the same blended acrylic polymer fiber. The resulting fabric was also found to have less tendency toward the collection of static electricity and was found to have improved wrinkle recovery qualities as the following table will show.

TABLE II Number Wrinkle Treatment of Static Half-life Recovery,

Washes Percent None 5 No half-life in 3 minutes. 76 With composition... 5 10 seconds 80 None 10 No half-life in 3 minutes. 74 With composition... 10 24 seconds 81 6 EXAMPLE III An aqueous dispersion was prepared containing 4 percent polyepoxide resin (Eponite 1 percent nonylphenyloxypoly (ethyleneoxy) ethanol (Igepal CT-430), 1 percent alkylphenol polyglycol ether (Nentronyx 600) and 0.5 percent zinc fluoroborate (40 percent solution).

This composition was applied to a length of fabric, the fabric being made from polyester fiber, Via padding but the composition may be applied by spraying, dipping, brushing, or any technique.

The length of fabric having been padded with aqueous composition was dried at 200 F. after which it was cured at 300 F. for six minutes, the resulting fabric was found to readily dissipate a charge of static electricity after five and ten washings as the following table will show.

TABLE III Treatment Number 01' Washes Static Half-life, Seconds EXAMPLE IV An aqueous dispersion was prepared containing 5 percent polyepoxide resin (Eponite 100), 1 percent nonylphenyloxypoly (ethyleneoxy) ethanol (Igepal CO-430), 1.25 percent alkylphenol polyglycol ether (Nentronyx 600) and 0.65 percent zinc fluoroborate (40 percent solution).

This composition was applied to a length of fabric, the fabric being made from polyester fiber via padding but the composition may be applied by spraying, dipping, brushing, or any technique.

The length of fabric having been padded with aqueous composition was dried at 200 F. after which it was cured at 300 F. for six minutes, the resulting fabric was found to readily dissipate a charge of static electricity after five and ten washings as the following table will show.

The application of Igepal CO430 only, gives an excellent initial static protection which, however, disappears after one washing.

Application of the antistatic finish of the present invention may be made to any form of the shaped structure including foams, films, plastic sheets and the like.

As described previously, the textile fabric is treated with an emulsion of a mixture of a polyepoxide and a compound of Formula I. Generally, the emulsion is prepared by dispersing the elements of the composition in water at room temperature with vigorous stirring. The concentration of the reactants in the emulsion may vary widely. A concentration as high as 25 percent may be used; however, more dilute emulsions containing from about 1 percent to about 7 percent of reactants are generally preferred. Any such suspension having a concentration suitable to provide from about a 0.5 percent to about 7 percent solids pickup based on the dry material is satisfactory. The reaction product can be applied to the structure by conventional methods such as dipping, padding and the like. After removal of excess liquid by wringing; the fabric is dried and cured, the drying and curing may be done in one operation.

Many different modifications of the invention may be made without departing from the scope and spirit thereof. It is contemplated that variations may be made in the percentages of the compounds used without greatly altering the antistatic characteristics of the fibers; therefore, the applicant does not wish to be bound by the numbers exactly as they appear above.

We claim:

1. A process of applying a durable, antistatic finish to a synthetic article comprising applying to the article an aqueous mixture consisting essentially of (1) a polyepoxide,

(2) a nonylphenoxypoly (ethyleneoxy) ethanol of the formula HH ll C=O C9H1BO C-O-(CH2CHz-O)n1CH3-CH2OH s i? H H wherein n is a whole integer no greater than about 10,

(3) an epoxide curing catalyst, and (4) a dispersing agent,

and thereafter reacting the polyepoxide and the nonyl- 8 class consisting of acrylic and polyester comprising applying to the article an aqueous mixture consisting essentially of (l) a polyepoxide (2) a nonylphenoxypoly (ethyleneoxy) ethanol of the formula IIIH /CO(OHz-CH2O)3OH2CH2-OH 5 1 H H (3) an epoxide curing catalyst, and (4) a dispersing agent, and theerafter reacting the polyepoxide and the nonylphenoxypoly (et-hyleneoxy) ethanol together.

7. A synthetic article treated by the process of claim 1. 8. A synthetic article comprised of a fiber selected from the class consisting of acrylic and polyester treated by the process of claim 6.

References Cited by the Examiner UNITED STATES PATENTS 2,752,269 6/1956 Condo et al ll7-l39.4 2,872,427 2/ 1959 Schroeder ll7l61 3,021,232 2/1962 Pretka 1l7-l38.8

WILLIAM D. MARTIN, Primary Examiner.

T. G. DAVIS, Assistant Examiner. 

1. A PROCESS OF APPLYING A DURABLE, ANTISTATIC FINISH TO A SYNTHETIC ARTICLE COMPRISING APPLYING TO THE ARTICLE AN AQUEOUS MIXTURE CONSISTING ESSENTIALLY OF (1) A POLYEPOXIDE, (2) A NONYLPHENOXYPOLY (ETHYLENEOXY) ETHANOL OF THE FORMULA 